Melt Crystallization of Ammonium Dinitramide Mixtures with Nucleation Additives: Structure Analysis by Means of X-Ray Diffraction in Addition with Imaging Methods

Even though Ammonium dinitramide (ADN) is a promising oxidizing agent for solid rocket propellants, a few obstacles still need to be overcome. To fulfill given requirements of propellant formulations spherical particles (so called prills) are preferred. To control the emulsion crystallization prilling-process in that manner to obtain ADN particles with a mechanical and thermally stable microstructure is subject of research at Fraunhofer ICT. In this work in-situ X-ray diffraction measurements and Scanning Electron Microscopy on mixtures of ADN with several dry additives were performed. Effects of these additives on ADN melt and recrystallization behavior have been studied. Several used additives prohibited successfully a super-cooled ADN melt and led to a homogeneous microstructure. In one sample uncommon three-dimensional geometric structures of ADN have been observed.