The Ni-plated carbon fiber as a tracer for observation of the fiber orientation in the carbon fiber reinforced plastic with X-ray CT

Microfocus X-ray computed tomography (XCT) is effective to evaluate the 3-dimensional (3D) structure (position and orientation) of the fillers in the composites. However, the observation of the carbon fiber (CF) in resin by XCT is not easy due to the small difference between X-ray attenuation coefficient of CF and that of resin. We conducted XCT scanning of carbon fiber reinforced plastics (CFRPs) containing Ni-plated CF. The fiber orientation can be clearly observed in CT images due to a large X-ray attenuation coefficient of Ni-plating. Ni-plated CF essentially showed the same fiber orientation as that of normal CF. We also carried out the 3D characterization of the fiber orientation in an injection-molded dumbbell specimen with weld line. The fibers around the weld line are oriented perpendicular to the longitudinal direction of the specimen.