The structure of the interface in carbon fibre composites by scanning auger microscopy

Scanning Auger microscopy (SAM) has been used to study the fiber /matrix interface of composite materials. This novel application of Auger spectroscopy enables further understanding of the mechanism of failure in composites when applied to carbon fiber-reinforced epoxy material. Initial work was carried out on carbon fibers prior to their incorporation into the resin matrix. Auger spectroscopy can be used to detect the presence of thin polymeric layers on the carbon fibers if a suitable, matrix-specific element is chosen to form the scanning Auger image. Two composite materials have been investigated. They differ from each other by the fracture mechanisms. In the case of unidirectional continuous fiber composites, a high volume fraction of conducting carbon fibers makes Auger analysis possible although the failure surface is predominantly polymer residues. For short-fiber composites the technique is more difficult considering the low volume fraction of fibers, but Auger spectroscopy enables the identification of microfailure mechanism and of the effect of fiber surface treatment on the failure mode. (Author)