A guanidine nitrate (GN)/basic copper nitrate (BCN) mixture is used as the main component of gas generators in an automotive airbag system. In this study, in order to search for novel additives that can reduce the amount of toxic combustion gases, we investigated the influence of the addition of metal oxides (ZrO2, Al2O3, MgO, TiO2, CuO, Cu2O, SnO2, V2O5, WO3, and MoO3) on the combustion behavior of the GN/BCN mixture. Combustion tests carried out using a chimney-type strand burner indicated that the burning rate of GN/BCN containing a metal oxide increased in comparison with that of additive-free GN/BCN. The composition of the combustion gas changed depending on the type of metal oxide added. The amount of CO included in the combustion gas markedly decreased in GN/BCN containing metal oxides having a low boiling point of less than 2300℃ (CuO, Cu2O, SnO2, V2O5, WO3, or MoO3). On the other hand, for GN/BCN containing Al2O3 or MgO, the NOx amount decreased and the CO amount was almost the same as that of additivefree GN/BCN. Analysis of the combustion residue showed that the metal oxide acted as an oxidizer to decrease the CO content, while Al2O3 and MgO acted as catalysts for the reduction of NOx. No significant change in the toxic gas composition was observed between GN/BCN containing TiO2 or ZrO2 and additive-free GN/BCN.
airbag, gas generator, guanidine nitrate, basic copper nitrate, combustion gas