An in situ investigation of microscopic infusion and void transport during vacuum-assisted infiltration by means of X-ray computed tomography

In situ vacuum-assisted infiltration experiments were carried out using synchrotron X-ray computed tomography (SXCT) to study the mechanisms of microfluid flow within a fiber tow. A single tow of E glass fibers was infused with a water and syrup blend using an apparatus designed and built for this purpose. The high resolution of the SXCT images allows the detailed reconstruction of individual fibers within the tow while the contrast between the different phases (air, fluid and fibers) was enough to track the fluid front position and shape as well as the void transport during infiltration. The ability of this technique to provide detailed information of microfluid flow and void transport in composite materials is clearly established. The fluid propagation at the microscopic level as well as the mechanisms of void transport within the tow were related to the wetting between the fluid and the fibers, the rheological properties of the fluid and the local microstructural details (fiber volume fraction, fiber orientation) of the fiber tow.