Nitrocellulose Thermal Decomposition And Cobalt Catalytic Mechanism Of Study

Combustion properties of propellants are the key performance for weapons to obtain stability and controllable ballistic characteristics, and the investigation on combustion properties usually started from the study of thermal decomposition process. Combustion catalyst can regulate and improve the thermal decomposition and combustion performance of the propellants. In this thesis, three aspects of work were studied. Firstly, Catalysts Preparation and Characterization; Secondly, thermal decomposition characteristics of NC were analyzed by TG-MS method. Thirdly, the catalytic mechanism of catalyst on the thermal decomposition of NC was studied.In this thesis, cobalt was prepared by the method of liquid-phase reduction using hydrazine as reducer, Co(NO3)2·6H2O as raw material. Cubic CoO was got by the method of solid-phase method. Cubic Co3O4 was gained by the method of liquid precipitation method. All the catalysts were characterized by Raman,XRD,SEM and so on. The thermal decomposition of NC propellant was studied via TG-MS method. The thermal decomposition of NC was completed intensively in a very short time at the temperature of 200℃. According to the thermogravimetry-mass (TG-MS) analysis, the gaseous products evolved during the thermal decomposition of NC propellant were H2O,HCN,CO(N2),HCOH,NO,CO2 and NO2(HCOOH) respectively.Co, CoO, Co3O4 were used as catalysts for the thermal decompotion of NC, respectively. Based on the results of thermogravimetry-mass (TG-MS) analysis, the integral intensities of individual ions were calculated and it was found that the addition of catalyst resulted in the increase of m/z=18(H2O+).44 (CO2+),46 (NO2+/HCOOH) MS signals, but the decrease of intensity of m/z=27(HCN+),28 (CO+/N2+),30 (NO+,HCHO+) MS signals during the thermal decomposition of NC propellant.The structures and morphologies of solid products after the thermal decomposition of NC propellant were characterized by XRD and SEM. It was shown that each of the catalysts has become Co powder. In addition, it can be seen that the morphologies of the catalysts have been completely changed by SEM analysis. After a careful analysis of solid products, it can be concluded that the catalysts changed to cobalt metal atoms or atomic cluster during the thermal decomposition of NC, and the cobalt metal atoms or atomic cluster may acted as the real catalytic species.