Contrast enhancement in visualisation of woven composite architecture using a MicroCT Scanner. Part 2: Tow and preform coatings

MicroCT scanning is a non-destructive method which was used to visualise tow architecture in woven composites, with the ultimate goal of three-dimensional model generation. It is difficult to discriminate between elements of carbon-fibre composites using MicroCT, particularly the region between co-aligned neighbouring tows. Methods used to facilitate visualisation by enhancing contrast during scanning were discussed in part one [Djukic LP, Herszberg I, Walsh WR, Schoeppner GA, Prusty BG, Kelly DW. Contrast enhancement in visualisation of woven composite tow architecture using a MicroCT Scanner. Part 1: fabric coating and resin additives. Compos Part A 2009;40:553–65.]. In order to improve upon these methods, tows were coated in a material of higher density and subsequently woven into a fabric. The most successful coatings were found to be gold and iodine. Adequate visualisations of glass tows were possible without contrast enhancement. These methods can be combined to allow multiple levels of contrast within a sample, as demonstrated with a three-dimensional woven preform. Three-dimensional reconstructions of interior tow architectures were made from the scans of contrast enhanced specimens.