Kazuo Hasue

In this study, based on the observed burning rate of 1H-tetrazole and ammonium nitrate mixtures at pressures of 1–10 MPa and temperatures of 238–358 K, equations expressing the burning rate as a function of pressure and temperature were derived. In general, the calculated burning rates were in good agreement with the observed values.

Ammonium nitrate has been attracting attention over the years as an oxidizer for clean gas-generating agents. Aminoguanidinium 5,5′-azobis-1H-tetrazolate was mixed with ammonium nitrate to improve its burning performance and the burning behavior of the formulations was studied by measuring the linear burning rate. The effects of particle size and composition ratio on the burning rate were studied. It was found that the mixture containing 50% ammonium nitrate by weight was the most promising composition. The particle sizes of fuel and oxidizer do not influence the burning rate.

The combustion characteristics of aminoguanidinium 5,5′-azobis-1H-tetrazolate (AGAT)/ammonium nitrate (AN)-based gas generating agents were studied by using a temperature-controlled chimney-type strand burner. Controlling the initial temperature at 243, 298, or 343 K, the mass burning rates of AGAT/AN = 50/50 were measured and the temperature sensitivities were deduced. The effects of CuO and MnO₂ on temperature sensitivity were studied. The temperature sensitivity equation as a function of pressure and initial temperature was also determined.

Recently, 5‐amino‐1H‐tetrazole is developed for practical use as a substitute for sodium azide, which is conventionally used as a fuel component of gas generating agents for automobile airbags. In this study, the combustion mechanisms of the mixtures 5‐amino‐1H‐tetrazole/potassium nitrate and 5‐amino‐1H‐tetrazole/sodium nitrate have been examined. It has been found that the Granular Diffusion Flame model is applicable to the tested samples even when a molten layer exists at the burning surface. In addition, it is shown that within the pressure range of 1–5 MPa, the greatest factor which affects the burning rate is the diffusion process. It is also demonstrated that the fuel component decomposes first, and the oxidizer decomposes next. Meanwhile, it has also been confirmed that the burning rate increases with an increase in pressure because the flame approaches the burning surface and the amount of heat transfer to the solid phase increases. In spite of a decrease in the amount of heat transfer from the gas phase to the solid phase and an increase in the thickness of the condensed phase reaction zone for a mixture with higher fuel content, there are little differences in the burning rates probably because of an increase in the rate of decomposition of the solid phase.