Fig. 1. Tips of untreated fibres from charge A (top) and charge B (middle), which showed evidence of tarry coatings on some fibres (bottom).Figure optionsDownload full-size imageDownload as PowerPoint slide
On few fibres, of charge B especially, there were occasional spots of an additional adhering material, which presumably is a tarry coating, known as a typical side product from graphitisation . Besides this BWX 46 contamination, there were no remarkable differences, observed by SEM, in the untreated fibres.
Cross-sections, or rather end faces of fibres, from charges A and B after heat treatment, are crustaceans shown in Fig. 2 to characterise the rim and core structure of the fibre. The morphology of the fibres were consistent throughout the thickness of the felt, and so any changes do not represent just a surface effect.
Fig. 2. End faces of fibres from charge A (left) and charge B (right) after activation at 403 °C (top), 525 °C (middle) and 575 °C (bottom).Figure optionsDownload full-size imageDownload as PowerPoint slide