Contrast-Enhanced Composites via Hafnium Oxide Nanocrystal-Coated Carbon Fibers

Carbon fiber reinforced polymers (CFRP) are of utmost importance in high-performance structural applications such as aerospace, automotive and wind energy. Modelling of their behaviour starts from accurate and straightforward geometry reconstruction, which is currently unfeasable due to a lack of Computed Tomography (CT) contrast. We explore the potential of hafnium oxide nanocrystals (HfO2 NCs) as CT contrast agents by coating the NCs on the carbon fiber surface. The enhanced CT contrast makes for a stark contrast difference between pure polymer matrix to carbon fiber fabric, allowing for automatic segmentation. To ensure a dense and well-dispersed coating, solution dipcoating and airbrushing were used. Both techniques yield drastic CT contrast improvements over a range of HfO2 NC concentrations on the interface between different tows. Furthermore, we explore the potential of an NC-airbrushed squared pattern of NCs as internal trackers in digital volume correlation (DVC), expanding the possible visualization and measurement techniques to understand CFRP behavior.