Combustion of Black Powder. Part 1: Thermo‐analytical studies

Abstract

An experimental programme is described, in which a number of thermo‐analytical techniques, differential scanning calorimetry (DSC), thermogravimetry (TG and DTG) are applied to investigate the combustion of black powder. The primary aim has been to investigate, and determine qualitatively and quantitatively, the nature of the solid products of combustion. Additionally, standard analytical techniques were applied, to a chemical analysis of the solid products, resulting from the electric arcignition of a sample of black‐powder, under ambient, open air conditions. The solid products formed 33% by weight of the unburned black powder, consisting of K2SO4 (15%), K2CO3 (11.5%) and small amounts of KNO3 and KNO2. The DSC, TG and DTG analyses suggest a mechanism for the combustion, based on phase changes and transition stages of sulfur and KNO3, and their interaction with charcoal.

Combustion of mixtures containing NaClO4, S and carbon

“…The first could be due to the oxidation of free S by NaC104 in the presence of charcoal whereas the broad peak at 355 ~ could be due to the oxidation of adsorbed S [9]. There was no such exothermic reaction between NaCIO4 and Safter or prior to the melting of NaC104 in case of a binary mixture of NaC104 and S (75:25) as evidenced in the case of KNO3 [1,10]. In the HSM it was also observed that during heating of this binary mixture all of the yellow sulphur just evaporated leaving white NaC104 crystals thus showing no reaction between S and NaCIO4 similar to KC104 [5].…”

“…As some of the water from the sample preparation stage is retained by NaC104, the ignition with nichrome wire [1,5] was not so abrupt as in the case of KC104 [5]. However, if the ternary mixture is heated to 95 ~ first, then ignition by nichrome wire produces a sudden flash.…”

“…KzSO4 is formed as a major solid product and about 56-57% solids are formed [1] along with CO2 as the major gaseous product [3,4]. In the search for a better oxidizer which could produce less solids but effective force of propulsion also, NaC104 is being investigated.…”

“…In black powder, KNO3 is used as an oxidizer [1][2][3] for the combustion of charcoal. KzSO4 is formed as a major solid product and about 56-57% solids are formed [1] along with CO2 as the major gaseous product [3,4].…”

A study on combustion behaviour of carbon-sulphur-sodium nitrate mixtures

“…The combustion of black powder [1][2][3] which has a traditional composition of KNO3 (75%), charcoal (15%) and S (10%) [4][5] has been studied in our laboratories. Although black powder is the oldest explosive known, it is still being used due to its peculiar properties [6].…”