L-155 Survey on State-of-the-Art Near-Infrared Emitting Compositions for Flares and Tracers

March 2009
Dr Ernst-Christian Koch (Energetic Materials)

For clandestine signalling and illumination purposes in the near infrared range (0.7 – 1.0 µm) pyrotechnic compositions based on either potassium and/or cesium compounds are used that are based on the intense emission lines of both K and Cs in the infrared.  These flare compositions contain silicon as a high-energy non-luminous fuel, which is known to burn in the condensed phase exclusively.  Furthermore, these compositions comprise nitrogen rich compounds like e.g. hexamine or azo dicarbonamide as blowing agents to “peel-off” the condensed reaction products.

Dim igniter and dim tracer-compositions are generally based on compositions having a low combustion temperature and mainly generating incandescent condensed reaction products. Typical oxidizers are the peroxides of barium, strontium and zinc and stannic oxide.  Typical non-luminous fuels comprise calcium silicide, charcoal, silicon, and calcium resinate.

Due to lack of highly reactive and sensitive magnesium NIR illuminant compositions are comparatively safe to handle and do not degrade as much as VIS-illuminant compositions.

Besides NIR tracers NIR illuminants comprise parachute signal flares for 26.5 and 40 mm as well as illuminating rounds for mortars in 60 mm and 120 mm.  For clandestine aerial reconnaissance 123 mm NIR illumination rocket can be applied.  NIR Trip-flares and stabilized illumination devices finally complete the palette of munitions.