Investigation Of High Burning Rate Gun Propellant And Its Burning Performances

To prepare the high burning rate propellants with superior performances, the method of preparing the porous propellants was put forward in this work. The gun propellants, in which the nitrocellulose is the main component, were foamed by the supercritical fluid foaming technology, and the high burning rate propellants were prepared in this work. The foaming process, the porous structure and burning characteristics of the foamed propellants were investigated in this paper, besides, the burning model of this novel porous propellants was put forward. The foamed oblate propellants were used to prepare the large-sized consolidated propellants with high burning rates, the mechanical properties and burning characteristics of the consolidated propellants were also investigated in this work. The main research contents and results are summarized as follows:1 The CO2 sorption and desorption in the propellants where the nitrocellulose is the main were investigated in this work. Based on the research results, several methods were used to explore the foaming process of NC-based propellants. The results indicate that a large amount of CO2 could be absorbed by the NC-based propellants, and the addition of energetic plasticizer to the NC-based propellants would greatly improve the foaming ability of NC-based propellants. Besides, in contrast with the rapid venting method, the temperature-induced foaming method would provide the large nucleation energy and is the suitable method for preparing the porous propellants.2 The TEGDN propellants were foamed by temperature-induced foaming method to prepare the porous propellants. The inner morphology of the porous TEGDN propellants was characterized by the scanning electron microscope, and the effects of process parameters on the final porous morphology were also investigated in this work. The research results indicate that the porous propellant grains prepared by temperature-induced foaming method exhibited the skin-core structure. Besides, the process parameters, the restrain effect and the energetic plasticizer content have an important influence on the porous structure of propellant grain.3 The quenched combustion experiment was used to explore the burning process of porous propellants, besides, the burning rate tester and closed vessel experiments were also used to investigate the burning characteristics of porous propellants. The results showed that the burning behaviors of foamed propellants were different from that of conventional compact propellants, and the burning process of foamed propellants deviated from the parallel-layer combustion. The porous core of propellant grain burns much faster than the compact skin of propellant grain, besides, the pore structure of foamed propellants which is influenced by the process parameters exerted an important impact on the burning performance of foamed propellants.4 Based on the research results of quenched combustion experiments, the combustion mode of foamed propellants were put forward in this work under several assumptions, the burning rate calculation method of foamed propellants were also proposed in this work. The burning rate of foamed propellants was calculated by this method, and the results showed that the calculated burning rate of foamed propellants with the novel method is closer to the real burning rate than that calculated by conventional method.5 To prepare a large-sized consolidated propellant with steady burning performance, the compact structure of consolidated propellants using foamed oblate propellants as fast burning fillers was put forward in this paper. The nitrocellulose and thermoplastic elastomer were mixed and used as the binder of the consolidated propellants. The mechanical and burning performance of the novel consolidated propellants were evaluated, besides, the effect of binder content, binder composition and the solvent ratio on the performance of consolidated propellants were also investigated in this work. The research results indicated that all the factors mentioned above had an important impact on the propellant performances. Based on the performance research of consolidated propellants, multi-perforation consolidated propellants which can be loaded as the propellant module were designed and prepared in this work, the performance of the multi-perforation propellants were also investigated. The research results showed that the loading densitiy of the consolidated propellants can even reach to 1.31 g/cm3 which is much higher than the conventional loading density 0.9-1.0 g/cm3 using small propellant grains. Besides, the large-sized consolidated propellants burned steadily even at low and high temperatures, and the progressive burning performance can be realized.