Nondestructive Evaluation Techniques for Composite Materials with Low Density Gradients

ABSTRACT: Energetic composite materials comprise crystalline energetic particles embedded in a polymer matrix. There is a need to gain insight into the microstructure and damage mechanisms of energetic composites via nondestructive evaluation. Applications of x-ray computed micro-tomography to resolve the microstructure of energetic composites are challenged by the low density gradient between the energetic particles and the polymer matrix. There is, however, a sharp contrast between the crystallinity of the crystalline (energetic) particles and the largely amorphous polymer matrix. Micro-tomography techniques relying upon x-ray diffraction (XRD) contrast thus promise to resolve the microstructure and damage mechanisms of energetic composites. An XRD-based approach to micro-tomography could also distinguish between different crystalline structures encountered in energetic composites. The proposed Phase I project will produce experimental proof of concept for the capabilities of x-ray diffraction contrast micro-tomography to resolve the microstructure and damage mechanisms of energetic composites with low density gradients. The Phase I effort will also design a blast containment system incorporating high-rate deformation capabilities to contain and deform the energetic composite specimens during x-ray diffraction contrast micro-tomography. BENEFIT: Integration of x-ray absorption & diffraction contrast micro-tomography would address market needs for resolving the microstructure and damage mechanisms of energetic and other composite materials with low density gradients as well as broad classes of polycrystalline materials. The new capabilities offered by these integrated systems are of value towards development and testing of a energetic composite materials and propellants that are of interest to the Air Force and DOD, and also to mining, rocket propellant and other industries. Development and testing of polycrystalline materials would further expand the fields of application of the technology. Diverse inorganic, metallic and organic materials, used in aerospace, power generation, electrical/electronics, and chemical/petrochemical applications, can be investigated via x-ray diffraction contrast micro-tomography.