Micro-/nano-alumina trihydrate and -magnesium hydroxide fillers in RTV-SR composites under electrical and environmental stresses

Abstract

High-voltage outdoor insulating materials face formidable challenges emanating from stresses such as electrical discharge, humidity, and UV radiation, propelling them perilously toward potential failure. To combat this, researchers explored novel materials to enhance insulator performance under these stresses. In this study, samples infused with micro-/nano-alumina trihydrate (ATH) and -magnesium hydroxide (MH) were tested with a base polymer (RTV-SR – room-temperature vulcanizing silicone rubber) during a 100 h electrical discharge aging process. They were simultaneously exposed to AC discharges, UV irradiation, and varying humidity levels. The study found a decline in hydrophobicity in all samples post-discharge exposure. Notably, composites with micro- and nano-fillers exhibited prolonged hydrophobic recovery under stresses such as medium humidity and UV irradiation. Scanning electron microscopy analysis displayed deep cracks and block-like structures on surfaces, particularly in samples R1 (50% micro-MH) and R2 (50% micro-ATH). Aged sections of R3 (10% nano-ATH) and R4 (10% nano-MH) showed heightened surface cracks compared to R5 and R6. Energy-dispersive X-ray analysis detected surface oxidation, emphasizing the severity of electrical and other stresses. FTIR results indicated minimal absorption peak reduction in co-filled samples after aging. These findings highlight the impact of co-filled composite insulators for robust insulating systems to withstand the hostile outdoor environment.

Keywords

• silicone rubber
• discharge aging
• hydrophobicity
• magnesium hydroxide