Preparation And Properties Of Modified Single-based Gun Propellant

In order to improve the combustion performance and mechanical properties of modified single-based gun propellant,a series of propellants satisfied the requirements of force constant and explosion temperature were prepared.In these propellants,a mixed nitrocellulose of B~#and C~#was used for a binder and RDX and nitroguanidine as energy additives.The thermal decomposition behavior of the propellant was studied by differential scanning calorimetry(DSC)and thermogravimetric analysis(TG).The mechanical properties of the propellant were tested by static compression testing machine and charpy impact tester.The safety of the propellant was measured by impact sensitivity(characteristic fall height),thermal sensitivity(5s burst point)and electrostatic spark sensitivity.Based on the above experiments,the effects of nitroguanidine concentration,nitrogen concentration of nitrocellulose,RDX with different particle size and NQ with different particle sizes and morphology on the thermal decomposition performance,stability,mechanical properties and safety properties of modified single-based propellants were analyzed and discussed.The main findings are as follows:The thermal decomposition of modified single-based propellants is divided into two processes.The first process is the thermal decomposition of mixed nitrocellulose,the second process is the decomposition process of RDX and NQ.With the increase of NQ concentration,the thermal decomposition temperature was improved,the amount of gas released in the vacuum stability test was decreased,and the thermal stability of the sample was improved.In addition,the mechanical properties decrease with the increase of NQ concentration.As the NQ concentration increases,the safety performance of the propellant meets the requirements.The higher the nitrogen concentration of NC in the propellant,the lower the thermal decomposition temperature,the amount of gas released in the vacuum stability test was increased,indicating that the thermal stability of the propellant is worse.The mechanical properties of propellant was improved through reduce the nitrogen concentration of NC.When the nitrogen concentration was 12.6%,the modified single-base gun propellant have a relatively high thermal decomposition temperature and the highest density in all samples,and the impact strength and compressive strength are relatively good.As the nitrogen content of the NC changes,the safety performance of the propellant sample meets the requirements.With the decrease of the particle size of RDX and NQ,the thermal decomposition peak temperature of the modified single-based gun propellant decreases gradually,and the gas release amount is also increased in the corresponding vacuum stability test,the thermal stability of propellant deteriorates.The addition of small particle size RDX and NQ to the propellant can improve the mechanical properties,but as the particle size increases,the mechanical properties gradually deteriorate.The mechanical properties of propellants containing long needle-like NQ are higher than those of spherical NQ propellants.As the NQ particle size decreases,the safety performance of the propellant sample meets the requirements.