Ammonium Dinitramide (ADN) - Prilling, Coating, and Characterizationl

Ammonium dinitramide (ADN) is the promising oxidizer, which is expected to be applied, e.g., in solid rocket propellants. The Manufacturing of spherical ADN particles (the so-called ADN-Prills) With useful morphology and reproducible quality is realized by means Of the emulsion crystallization process. The yet remaining drawback of ADN is the less compatibility with common curing agents used in most binder systems. This incompatibility Should be overcome by coaling the ADN particles. For this purpose, the fluidized bed technology was established at Fraunhofer ICT. Nowadays. two coating equipments (lab-scale and field-scale) are available, both modified for the processing of hygroscopic and explosive materials. Different polymeric coaling materials have been tested, and turned Out to be suitable for application in the fluidized bed. The properties Of the coated ADN particles have been characterized by microscopy. particle size investigation. Specific surface area measurement, and a very special Measuring instrument. which allows to detect the crushing strength of individual particles. It is to be seen that the ADN-Prills can be coated separately and With Uniformly thin layers. It has also been verified that the mechanical stability of particles can be increased by coating them. The compatibility of coated and uncoated ADN-Prills and isocyanate containing binder systems was investigated by microcalorimetric measurements and vacuum stability tests. It was proved that the compatibility could be increased by coating the ADN-Prills with polyacrylates, HTPB, or GAP.