The application of silicon as fuel in common pyrotechnic and explosive compositions is reviewed. For part V see Ref. [56].

Special Materials in Pyrotechnics: VI. Silicon - An Old Fuel with New Perspectives

Thermal analysis of pyrotechnics

Chemical characterization of residues from military HC smokepots

The addition of metal oxides to silumin-hexachloroethane pyrotechnic smoke mixtures makes ignition on a hot plate more difficult in the order aluminium oxide < zinc oxide < magnesium oxide. Evidence is presented that suggests that aluminium oxide inhibits ignition by acting as an inert diluent separating the active reactants whereas the effect of magnesium oxide is believed to be chemical in nature. The addition of small amounts of ferric oxide or potassium iodide has little effect on the onset of smoke formation in a silumin-hexachloroethane-zinc oxide composition but promotes the transition from smoke to flame reaction. In contrast small amounts of either iodine or trityl chloride inhibit the onset of the smoke reaction. A mechanism is proposed for the ignition of silumin-hexachloroethane compositions that accounts for these observations.

Smoke Generators. III. The ignition of pyrotechnic white smoke compositions containing hexachloroethane, silumin and metal oxides using a heated metal surface

The sections in this article are


15.1
Introduction

15.2
Characterization of Pyrolants
15.2.1
Thermochemical Properties of Constituents
15.2.1.1
Polytetrafluoroethylene (PTFE)

15.2.1.2
Poly(Carbon Monofluoride) (PMF)

15.2.1.3
Vinylidene Fluoride Based Copolymers

15.2.1.4
Hexachloroethane (HC) and Hexachlorobenzene (HCB)




15.2.2
Thermochemistry of Pyrolants




15.3
Ignition and Propagation
15.3.1
Ignition

15.3.2
Propagation




15.4
Combustion Phenomenology and Spectroscopy

15.5
Technical Applications
15.5.1
SHS

15.5.2
IRCM – Flares

15.5.3
Metal–Halocarbon Obscurants




15.6
Safety

15.7
Outlook

15.8
Acknowledgment



Keywords:

combustion;
high explosives;
metal–halocarbon pyrolants;
nanostructures;
decoy flares;
obscurant

Metal-Halocarbon Pyrolant Combustion

The ignition by electrically heated coil of two smoke generators containing hexachloroethane and silumin, one of which also contains zinc oxide, has been investigated. The physical conditions of consolidation, that is pressing load (between 7.9 × 106 kg/m2 and 3.1 × 107 kg/m2) and diameter of container (between 1.27 cm and 2.54 cm), have been shown to have no effect on the ease of ignition of each mixture. Addition of zinc oxide increases the minimum temperature of ignition from about 443 K to about 973 K and the minimum heating rate for ignition from about 2.5 watt to about 8 watt. The effect of zinc oxide is believed to be chemical rather than physical in nature.

Smoke generators. I. The Ignition of Pyrotechnic White Smoke compositions containing hexachloroethane and silumin by means of an electrically heated coil

A small sealed tube has been used to study the reaction between hexachloroethane and silumin, which is important in certain types of smoke generating pyrotechnics. Standard amounts were heated at 483 K in a 12−cm3 tube. Products identified were aluminium chloride and tetrachloroethylene. The effects of added oxides were noted. Zinc oxide, magnesium oxide and cupric oxide inhibited the reaction. Ferric oxide accelerated the reaction and stannous oxide, zirconium dioxide and titanium dioxide seemed to have little effect. Other substances found to inhibit the reaction were ammonium chloride, water and ortho-chloroaniline. Pentachloroethane was found as a product when water was present indicating the formation of pentachloroethyl radicals.

Smoke generators. IV: The ignition of loose powder mixtures of pyrotechnic white smoke compositions containing hexachloroethane and silumin in sealed tubes

Simultaneous differential thermal analysis with thermogravimetric analysis has shown that the inhibition of the ignition of silumin-hexachloroethane smoke generators by zinc oxide is not due to the adsorption of hexachloroethane vapour on zinc oxide. Analysis of this and previously reported evidence suggests a free radical mechanism for the reaction of aluminium with hexachloroethane. Zinc oxide inhibits this by competition for radicals.

M. R. Williams

Papers

Smoke generators. I. The Ignition of Pyrotechnic White Smoke compositions containing hexachloroethane and silumin by means of an electrically heated coil

Smoke Generators. III. The ignition of pyrotechnic white smoke compositions containing hexachloroethane, silumin and metal oxides using a heated metal surface

Smoke generators. IV: The ignition of loose powder mixtures of pyrotechnic white smoke compositions containing hexachloroethane and silumin in sealed tubes

Smoke generators. V. Thermochemical investigation of pyrotechnic white smoke compositions containing hexachloroethane and silumin