Failure analysis of a field brittle fracture composite insulator: characterisation by X-ray photoelectron spectroscopy analysis

In the present work, a field brittle fracture composite insulator was collected and examined with the purpose of obtaining a better understanding of the failure features. Firstly, the macroscopic and microscopic fractography of this fractured composite insulator was observed confirming that the classical brittle fracture morphology features appeared in this field failed composite insulator. Secondly, the X-ray photoelectron spectroscopy (XPS) analysis was performed on the fracture surface of the glass-fibre-reinforced polymer rod. By examining the XPS survey spectra and high-resolution XPS spectra for nitrogen, sulphur, silicon, calcium, aluminium, boron and carbon elements, the type of the glass fibre and the acid source responsible for this brittle fracture composite insulator were confirmed. Furthermore, the oxidation of the silicate network of glass fibre at the fracture surface was first observed, meanwhile, the oxidation of the epoxy resin matrix was also observed. The leaching of non-silicate constituents leading to a high-silica glass fibre was also observed; moreover, in comparison with the calcium and aluminium elements, the boron element resides in the silicate network was more preferential to be leached. The present work provides an insight into the brittle fracture in high voltage composite insulator from chemical properties point of view.