每年出版 6 期
ISSN 打印: 2150-766X
ISSN 在线: 2150-7678
Indexed in
ON CHEMICAL KINETICS OF THE IGNITION OF AP / NSAN / INERT BINDER COMPOSITE PROPELLANTS
摘要
This work concerns the ignition behaviour of ammonium perchlorate / non-stabilized ammonium nitrate / hydroxyl terminated polybutadyene and ammonium perchlorate / non-stabilized ammonium nitrate / polyurethane composite propellants. All the compositions were formulated with 80 % by weight of solid oxidant mass and 20 % by weight of bulk (pre-polymer, plasticizer and curing agent) binder system. In both type of compositions the cases 0 %, 20%, 40 % and 60 % of non-stabilized ammonium nitrate weight content, of the total solid mass, were studied.
The experimental apparatus used in this work for the measurement of ignition delays of the propellants, in ambient air and at atmospheric pressure, was composed of an electrical furnace, a pneumatic system for rapid introduction of the propellant samples and peripheral devices allowing real time control of the process and data acquisition.
The results obtained showed that increasing non-stabilized ammonium nitrate content caused shorter values of the ignition delay. Further interpretation of the experimental data was made assuming a first order rate controlling reaction, with constant reactants' consumption during the pre-ignition period. As the calculated values of the activation energy in the lower temperature range were always lower than those obtained for the higher experimental temperature, this type of evolution indicated that the ignition mechanism of this type of composite propellants could be described in two independent phases, corresponding Phase I to the occurrence of heterogeneous ignition reactions while homogeneous gas phase ignition reactions were characteristic of Phase II. The transition temperatures between Phases I and II were calculated. The results obtained demonstrate clearly that partial substitution of ammonium perchlorate by non-stabilized ammonium nitrate in the propellants' formulation shifts the transition temperature to lower levels, increasing in this way the domain of occurrence of homogeneous ignition.