Non-destructive material testing using lattice-based phase-contrast X-ray imaging

Grid-based phase-contrast X-ray imaging extends conventional X-ray imaging with two more image information, the differential phase image and the dark field image. While the differential phase image is sensitive to the smallest X-ray deflections, the dark field image contains structural information in materials. A dark field signal is due to scattering on granular, porous, or fibrous structures on the order of microns. This i.e. fine cracks or air inclusions are visualized in materials that are not visible in the conventional X-ray image. In addition, the dark field image has a directional dependence that can be used to determine the orientation of non-directly resolvable fiber structures. In this paper, the potential of this novel X-ray imaging method is presented and evaluated using a phase-contrast X-ray scanner. There are fields of application in the non-destructive testing of materials for the detection of cracks, air pockets and structural defects, i.e. by impact damage, presented in carbon fiber reinforced plastic parts, foamed materials or welds in aluminum parts.