A fundamental study on ignitability improvement was investigated by the addition of various metal oxides (MoO3, V2O5, WO3, TiO2, NiO, AgO, Ag2O, BaO2) to the 5-amino-1H-tetoirazole (HAT) –Sr(NO3)2 (SrN) mixture, which has already been used in practical application as a non-azide gas generant.
The 10wt.% addition of MoO3 or V2O5 was found to lower the ignition temperature compared with that of the HAT-SrN binary mixture (425°C); ignition temperature was 195°C by addition of MoO3 and 260 by addition of V2O5. It was clear that these oxides improved ignitability, acting not as an oxidizing agent but as a catalysis. An oxide with high oxidizability, such as AgO, does not always contribute to improvement of the ignitability.
The kinetics parameter of the decomposition was investigated for the HAT and its mixtures by carrying out of isothermal decomposition. The addition of MoO3 or V2O5 changed the rate equation of the decomposition from a first order equation to an autocatalytic one. These oxides seemed to be concerned involved in the cleavage reaction of the tetrazole ring by the same catalyst mechanism, though the mechanism was not clear.
The decomposition temperature of the oxidizing agent was lowered by the addition of most metal oxides used in this experiment, and was most lowered by addition of V2O5. The reactivity of SrN with HAT was promoted due to the decomposition of SrN at the lower temperature, which might explain the lower ignition temperature.
エアバッグ用ガス発生剤として既に実用化されている5-アミノ1H-テトラゾール(HAT)組成物に 関して, 着火性改良を目的として種々の金属酸化物(MoO3, V2O5, WO3, TiO2, NiO, AgO, Ag2O, BaO2,)が添加された。添加量は､HAT-SrN2成分混合物に対して外割で10wt.%とした｡ HAT-Sr(NO3)2混合物系の最低発火温度は, Mo03の添加によって425℃から195℃へ, V203の添加によって260℃ まで低下した。これらの酸化物は酸化剤としてではなく, 触媒として系に作用した, AgOのような高い酸化力を持つ酸化物は, 最低発火温度の低下に必ずしも寄与するわけではないことが明らかとなった｡HATならびに金属酸化物との2成分混合物について等温分解を行い, 分解の速度パラメータを検討した。分解反応は, 発火温度の低下に寄与するMoO3,V2O3添加系では自触媒反応の式に, HAT単体ならびに他の酸化物添加系では1次反応の式に最もよく適合したMoO3,V2O3は,HATの分解に対して同じ触媒作用を持つことが推測された｡ 一方, 酸化剤であるSr(NO3)の分解温度も種々の金属酸化物の添加によって低下する結果となり, V205の添加効果が最も大きかった。より低い温度でSr(NO3)2, が分解することで,HATとの反応性が促進されると推測された｡