Design And Study Of Guanidine Nitrate/Basic Cupric Nitrate (GN/BCN)Gas-generating Agents

A kind of guanidine nitrate and basic cupric nitrate (GN/BCN) gas-generating agent is studied in this paper. The determination factors of thermal decomposition mechanism and combustion characteristics of GN/BCN gas-generating agents for airbag application are investigated by the thermogravimetry-differential scanning calorimetry-mass spectrmetry-Fourier transform infrared spectroscopy (TG-DSC-MS-FTIR), closed bomb and automatic calorimeter. And the optimal gas-generating agent composition is determined.Firstly, because of the low combustion temperature (1901K) and large gas production (3.01mol·(100g)-1), guanidine nitrate/base copper nitrate (GN/BCN) gas-generating agent is chosen.Secondly, the thermal decomposition mechanism of the fuel (GN) in the GN/BCN gas-generating agent is studied, and the thermal decomposition of GN can be divided into four stages:1) the melting of GN happens about213℃;2) the main decomposition of GN begins at about280℃and completes at350℃(72.8%mass loss), the decomposition reaction equation is[C(NH2)3]+NO3-=HNO3+NH3+H2N-C≡N, and the activation energy is180kJ·mol-1;3) a kind of polymer production called Melon is prepared from the intermediate (H2N-C≡N) by multi-step polymerization and a NH3is released;4) high temperature decomposition of Melon is happened.And then the thermal decomposition mechanism and combustion characteristics of GN/BCN gas-generating agent are studied. The thermal decomposition of GN/BCN mixtures could be divided into three stages, including the dissociation and escape of crystal water, solid (GN)-solid (BCN) phase reaction and liquid (GN)-solid (BCN) phase reaction. The gases evolved from GN/BCN mixtures are determined to be H2O, N2and N2O. H2O and N2are the major gases for the thermal decomposition of GN/BCN mixtures. When mass ratio of GN/BCN is35.57/64.43, the reaction temperature is the lowest; the combustion speed is the fastest, and the ignitability is the best.At last, the combustion characteristics of gas-generating agent are improved by adding the ammonium perchlorate (AP) and potassium nitrate. The reaction heat of mixtures becomes higher with an increase of AP and KNO3in GN/BCN/AP/KNO3mixtures. The AP and KNO3could improve ignitability and increase burning velocity of GN/BCN gas-generating agent, but could not change the gas production basically.When mass ratio of GN/BCN/AP/KNO3is55.20/24.13/10.63/10.04, the burning rate is the fastest (0.867mM·s-1).