Combustion of some zinc-fuelled binary pyrotechnic systems

Combustion studies of several binary pyrotechnic systems using zinc as fuel and one of the oxidants: PbO₂, Pb₃O₄, PbO, BaO₂, SrO₂ or KMnO₄, are reported. Combustion was very sensitive to compaction, and only mixtures of Zn PbO₂, Zn Pb₃O₄ and Zn KMnO₄ sustained combustion when compacted. In all of the systems studied, the temperatures measured during passage of the combustion front past an imbedded thermocouple rapidly rose above the melting point of zinc. Burning rates were recorded for the Zn PbO₂ system compacted under 50 MPa, and the Zn KMnO₄ system under 50, 100 and 150 MPa. Thermochemical and kinetic data were determined where possible. Combustion mechanisms are suggested, involving condensed phase, diffusion-controlled reactions and gas-phase reactions occurring in parallel. Analysis of residues shows that ZnO is the major product in the Zn PbO₂ and Zn Pb₃O₄ systems, and that mixed zinc oxides are possibly the major products of the Zn KMnO₄, Zn BaO₂ and Zn SrO₂ systems.