Combustion Behavior of the Inorganic Nitrates‐Based Compositions Part I

Abstract

Combustion behavior of inorganic nitrates (KNO3, NaNO3, CsNO3, Ba(NO3)2, Sr(NO3)2, Pb(NO3)2, and NH4NO3) based energetic materials in wide range of pressure (0.1–18 MPa) was studied. Samples have the same binder and differ in combustion temperature due to a change of oxidizer excess ratio (α). It is shown that compositions differ in the burning rate, in its dependence on pressure. The extreme dependence of burning rate on α is established. The combustion temperature of the samples was experimentally determined.

Combustion Behavior of the Inorganic Nitrates‐Based Compositions. Part II: Effect of Al and Al‐Mg Alloy on Burning Rate

“…Ba(NO 3 ) 2 -based sample with α = 1 does not burn at atmospheric pressure. The experimental temperature of their combustion is much lower than the calculated one [1]. Factory standard oxidizers with 90-160 μm particle size and 99.5-99.8 % purity were used.…”

“…Basic samples (Table 1) that significantly differ in the values of the calculated (T calc ) and experimental (T exp ) temperatures and also in the burning rate (r b ) were selected from [1]: -the fastest-burning samples based on KNO 3 and CsNO 3 with α = 0.72, as well as a slow-burning KNO 3 based sample with α = 1. -a slow-burning sample based on NaNO 3 (α = 0.72) with a burning rate at atmospheric pressure is 3.5 times lower than that KNO 3 -based sample with the same α (0.72).…”

“…The plasticizer-dibutyl phthalate-was added last. Samples have been made using rolling (0.6 mm roll gap) and continuous pressing extrusion as in [1].…”

“…In [1] combustion regularities in a wide pressure range of metal-free compositions based on the same organic binder (phenol-formaldehyde resin plasticized by dibutyl phthalate) and various inorganic nitrates were studied (0.1-18 MPa). Some combustion patterns are the same, while others show a different behavior, for example: -some samples do not burn at atmospheric pressure; -maximum combustion rate at all pressures is achieved with a different ratio of oxidizer and fuel, characterized by the oxidizer excess ratio α (i. e., the balance of the oxygen amount in the composition to the amount required for complete combustion); -the burning rate's dependency on pressure for some samples consists of two sections with different n values in the Vielle's law r b = ap n , while it is unambiguous for others; -the experimental combustion temperature of the compositions, depending on the α and pressure, may coincide with the calculated one, be it higher or lower.…”

“…Some combustion patterns are the same, while others show a different behavior, for example: -some samples do not burn at atmospheric pressure; -maximum combustion rate at all pressures is achieved with a different ratio of oxidizer and fuel, characterized by the oxidizer excess ratio α (i. e., the balance of the oxygen amount in the composition to the amount required for complete combustion); -the burning rate's dependency on pressure for some samples consists of two sections with different n values in the Vielle's law r b = ap n , while it is unambiguous for others; -the experimental combustion temperature of the compositions, depending on the α and pressure, may coincide with the calculated one, be it higher or lower. Since many high-energy pyrotechnic compositions contain metallic fuel, it was necessary to perform a detailed study of its effect on the combustion rate of the systems studied in [1]. The importance of systematic research is also due to the well-known results on the complex effect of aluminum on the regularities of combustion of double-base [2] and composite modified propellants based on ammonium perchlorate [3][4][5] and ammonium nitrate [6].…”