Effect of wettability and textile architecture on fluid displacement and pore formation during infiltration of carbon fibrous preforms

We seek to address how air entrapment mechanisms during infiltration are influenced by the wetting characteristics of the fluid and the pore network formed by the reinforcement. To this end, we evaluated the behavior of two model fluids with different surface tensions, infiltrating three carbon fiber reinforcements, by means of X-ray radiography. We also assessed initial (dry) and final (wetted) states for each experiment by performing X-ray CT scans. We found that the fluid characteristics strongly affect the flow front patterns and pore filling events for a given fabric architecture. Two main promoters of snap-off events are involved in capillary dominated flows: a very wetting system leading to corner flows and the fabric bundles oriented perpendicular to the flow acting as obstacles, specifically in fabric architectures prone to variations in nesting. Finally, we evaluated the applicability of a pore network model to further link preform architecture and void formation.

Automated summary

This study investigates the influence of wetting characteristics and pore network of reinforcement materials on air entrapment mechanisms during infiltration. X-ray radiography and CT scans were used to evaluate the behavior of different model fluids infiltrating carbon fiber reinforcements. The results show that fluid characteristics strongly affect flow front patterns and pore filling events in different fabric architectures. Wetting system and fabric bundle arrangement perpendicular to the flow were found to be the main factors promoting snap-off events in capillary dominated flows. The applicability of a pore network model in linking preform architecture and void formation was also evaluated.