Investigation of the Combustion and Radiometric Behaviour of Magnesium-Teflon-Viton (MTV) Decoy Flares by Partial Replacement of Magnesium

Worldwide, studies are still being made to enhance the radiometric performance of the MTV composition, i.e. a composition of magnesium (Mg), polytetrafluoroethylene (PTFE, commonly called “teflon”) and Viton®, used in infrared (IR) decoy flares. In this study, the Mg fuel was replaced to modify the radiometric performance of the baseline MTV composition in terms of IR intensity and/or linear burn rate, along with the IR intensity ratio. To partially replace Mg, the fuels used were alloys: magnalium (Mg-aluminium (Al), 50:50) and boron Al ligature (BAL), a non-metal: silicon (Si), and organic fuels: 1,5-dinitronaphthalene (1,5-DNN) and 4-phenylazophenol (4-PAP). Composition batches of 100 g were prepared by replacing the Mg fuel, ranging from 5 to 25 wt.%, in the baseline MTV composition. The IR intensity in the 1.8-2.6 and 3-5 μm wavebands versus burn time was measured using a dual-band radiometer. The calorific value (Cal-Val), impact, friction and spark sensitivity measurements were obtained for all of the compositions. It was found that the IR intensities obtained were highest with the replacement by Magnalium, while those with organic fuels were the lowest. The maximum IR intensity was obtained at 5 wt.% replacement with Magnalium, which is 28.5% higher in the 1.8-2.6 μm range and 21.1% in the 3-5 μm range, and the linear burn rate was 9.8% lower than the baseline MTV composition. The IR intensity ratio was the lowest at 0.97 when 20% 4-PAP was partially replaced in the baseline MTV composition. The REAL thermochemical code was used to predict various equilibrium parameters of the MTV compositions. The thermochemical data was correlated with the spectral plot of the MTV compositions obtained by using an SR-5000N IR radiometer.