Inhibitors and Catalysts for the Exothermic Decomposition of Ammonium Perchlorate

摘要

In order to enhance extinguishment reliability of controllable solid-propellant motors, an investigation has been made by differential thermal analysis to search for additives or techniques that could eliminate or inhibit the normal first exotherm of propellant grade ammonium perchlorate (AP). It was found that the temperature at which this first AP exotherm occurred could be raised 85C by adding 1.5% ammonium hexafluorophosphate. The additive was also effective when fluorocarbon binder was in contact with the AP. A series of tests was made of the catalytic effect on this exotherm of traces of impurities in AP. Although the first AP exotherm was strongly catalyzed by as little as 0.04% of copper nitrate, the catalysis was suppressed by the NH4PF6 additive. The burning rate was increased by adding 0.1% Cu or Zn salts. Independent tests in a combustion-bomb and in a motor have demonstrated the increased extinguishment reliability suggested by the thermal analysis curves. The effect on AP decomposition and combustion exotherms has also been tested for a series of additives consisting of other ammonium salts, flame retardants, Lewis acids, and transition metal compounds. (Author)