Studies On Process Technology Of High Progressive And Large Web NQ-based Gun Propellant

For the study of gun propellant charge, there were two fundamental requirements, one is utilizing high energy gun propellant efficiently through studying the most appropriate principle of energy release, the other is making full use of gun barrel's bearing ability to increase muzzle velocity and firing range of gun. High progressive combustion propellant and low temperature sensitivity charge technology are used to enhance energy utilization of gun propellant and muzzle kinetic energy, meanwhile increasing gun power to interior ballistic guideline of longer barrel gun without any change in original design. For above purpose, this thesis focused on developing high progressive and large web nitroguanidine-based propellant which was appropriate to the new type charge system, and forming mature process technology.Several gun propellant formulations and the combustion property at constant volume and interior ballistic property evaluation tests of high progressive 37-hole and 19-hole propellant were studied. The results showed that Propellant SG-15 possessed such characteristics as high powder force and moderate heat, so both of high progressive large web 25/37 nitroguanidine-based propellant and unequal large web 24/19 coated propellant made from this formulation could meet the requirements of propellant applied to the new type charge system with high muzzle velocity and chamber pressure.A new mould for high progressive 37-hole nitroguanidine-based propellant was designed. Through increasing the height of mould forming section reasonably, arranging mould needle according to cohensive coefficient and selecting easy-to-fix disc type needle holder, progressive 37-hole nitroguanidine-based propellant's shortcomings in quality were solved, such as loose, cohensive etc. Furthermore, characteristic parameter computing program for lace 37-hole nitroguanidine-based propellant was developed using visible programming method.The influence of quality of material on progressive 37-hole nitroguanidine-based propellant and related countermeasures were studied. The obtained results revealed that the internal quality of nitrocellulose, one of the main materials for nitroguanidine-based propellant, would extensively influence the combustion behavior of finished propellant.Additionally, process technology for high progressive 37-hole nitroguanidine-based propellant was discussed. Processing conditions, such as charging sequence, gelling time and temperature, solvent ratio, alcohol/ketone ratio, output time and storage time of gelled propellant, compression pressure and time, the cutting, airing and drying of grain, were tested and then optimized. Finally, processing conditions and control requirements which were suitable to progressive 37-hole nitroguanidine-based propellant were confirmed. The results showed that physical and chemical properties of batches of propellant were eligible and showed little batch difference. Compared with SEM (scanning electron microscope) photograph of standard propellant sample, nitroguanidine-based propellant had excellent compactibility and microscope quality, and each ingredient was arranged orderly.Coating technology of unequal large web propellant was analyzed. The main factors influencing the quality of coating propellant included manufacturing equipment, shapes of base propellant, flame retardants content in outer coating-layer, wind temperature, wind rate, exposed-perforation ratio, percentage of plugged hole at coating initial segment, and the preparation, measurement and proving and charging speed of coating solution. The research results indicated that there was corresponding relationship between percentage of plugged hole at coating initial segment and exposed-perforation ratio at interruption tests. By proving and measuring coating solution, percentage of plugged hole at coating initial segment could be controlled, and then exposed-perforation ratio of propellant could be controlled effectively. Batches of coating propellant fabricated through optimized coating technology showed eligible physical and chemical properties, excellent low-temperature sensitivity, negative growth of chamber pressure increment at high temperature and outstanding ballistic repeatability.Generally speaking, once high progressive, large web 37-hole nitroguanidine-based propellant and large web coating propellant were used in the new type charge system, the muzzle velocity of gun could be efficiently increased and the maximum chamber pressure decreased. The studying and development of high progressive 37-hole nitroguanidine-based propellant made a primary breakthrough in the field of process technology of nitroguanidine-based propellant with more than 19 holes in our country. And the research results provided definite technological support for extended range modular charge technology and unimodular charge technology.