Investigation of pyrotechnic MTV compositions for rocket motor igniters

Abstract

Introduction P compositions based on magnesiumTeflon (MT) formulations are characterized by many advantageous properties as rocket motor igniter materials: high-energy content, low hygroscopicity, high degree of safety in preparation, low temperature and pressure dependence of the burning rate, ease of igniter pellet or grain fabrication, favorable aging characteristics, stable burning at low pressures, and low production costs. Viton A copolymer is frequently added to the binary MT mix to increase homogeneity and facilitate product fabrication (by consolidation, extrusion, or injection molding), without a substantial effect on combustion thermochemistry. In addition to excellent resistance to environmental deterioration, magnesium-TeflonViton (MTV) compositions have been noted for good ignition source characteristics. The existence of very hot solid and liquid particles and condensible and reactive species in MTV combustion products enables fast heat transfer to a solid fuel/propellant surface or to combustible gas mixtures by almost all possible modes: conduction from impinging solid particles, forced convection from gaseous species, high thermal radiation, exothermic condensation and solidification, etc. Soft ignition of solidpropellant motors (defined by low motor pressurization rate and absence of an ignition peak), which is very desirable in certain propellant grain configurations, is readily obtainable with MT or MTV pellets or granules. For given specific motors and igniter mass flow rates, pyrogen igniters with MTV charges achieved shorter ignition delay times than propellant charges for similar flame temperatures.