Impact of Gamma-Irradiated SiR-Al2O3 Nanocomposites and Degradation Diagnosis Using LIBS Method

The present study elucidates the impact of gamma irradiation on the thermal properties of silicone rubber (SiR) nanocomposite insulation. Contact angle measurements, water droplet-initiated corona discharge studies, and laser-induced breakdown spectroscopy (LIBS) studies are combined to provide a better understanding of the materials’ dielectric and thermal properties subjected to different irradiation dosages. The results show that the contact angle and the water-droplet initiated corona inception voltage decrease with increasing nanofiller content and gamma irradiation dosage. Analysis of the dielectric properties of the material following gamma irradiation shows that the cole–cole double relaxation model fits well with the permittivity measured at different temperatures for both virgin and gamma-irradiated specimens. The coefficient of thermal expansion, deduced from the measured dielectric parameters, decreases with the increase of alumina nanofiller content and with the dosage of gamma irradiation. LIBS studies indicate that the ablation depth of the virgin and gamma-irradiated specimens becomes smaller when the filler content is increased. The coefficient of thermal expansion correlates directly with the plasma temperature measured using LIBS spectra of the nanocomposite material for nonirradiated and irradiated specimens.