Contrast enhancement in visualisation of woven composite tow architecture using a MicroCT Scanner. Part 1: Fabric coating and resin additives

MicroCT scanning is a non-destructive inspection method which was used to visualise tow architecture in woven composites with the ultimate goal of three-dimensional model generation. This has been achieved in the past for glass fabric composites, but is problematic when applied to carbon fabrics. Using X-rays, it is difficult to discriminate between elements of the composite, particularly the region between co-aligned neighbouring tows. This presents difficulty when viewing such composites using X-ray MicroCT scanning. Additives were used to enhance contrast during scanning. The most successful techniques were coating of fabrics with gold, copper, and an iodine contrast agent. Resin particle additive techniques were also trialled, with limited success. Good visualisations of glass fabrics were possible without contrast enhancement. Three-dimensional reconstructions of interior tow architectures were then made from the scans of contrast enhanced specimens. This research can be viewed as a starting point in developing methods for generating contrast between neighbouring tows within a three-dimensional woven preform using MicroCT scanning.