Candidate: Safi Ullah Butt
Date: June 17, 2026
Time: 10:00 AM – 11:00 AM
Location: Online — contact the candidate for more information.
Supervisor: El-Hag, Ayman – Ghunem, Refat
Abstract:
Silicone rubber is the preferred housing material for outdoor insulators due to its inherent hydrophobicity which arises from the diffusion of low molecular weight (LMW) components from the bulk to the surface. The hydrophobicity recovery capability of silicone rubber delays the induction of dry-band arcing. However, environmental stress factors such as moister, contamination, and salt deposits will eventually destroy the hydrophobicity of silicone rubber, making the housing material susceptible to dry-band arcing. The heat generated from dry-band arcing may subsequently lead to tracking and erosion of silicone rubber housing material. The housing material is modified with the addition of inorganic fillers to impart tracking and erosion resistance.
In highly polluted industrial environments, an additional and particularly aggressive stress factor arises from acidic exposure where acid is produced from the oxides of nitrogen or sulfur reacting with moister during the events of acid rain or be a byproduct of corona discharges. Acidity promotes physiochemical changes and the cracking of the silicone rubber housing, facilitating the moister and acidity ingress into the fiberglass core leading to the stress corrosion cracking (SCC) of the fiberglass rod and brittle fracture failure of the insulator. Insulator failures pose an imminent threat to the reliability of the power grid. In the existing material designs, fillers are incorporated into the base silicone rubber primarily on the flame retardancy approach to impart the tracking and erosion resistance, while the effect of acidity is generally not considered. Consequently, the current material designs remain vulnerable to acidity degradation and consequent SCC and brittle fracture failure of the insulators. It is critical to modify the design of the housing material that can effectively withstand the harsh acidic conditions. The resistance to tracking and erosion is an important material design criterion. Therefore, it is essential to understand the effect of acidity on the tracking and erosion resistance of silicone rubber housing material for the development of suitable material design for harsh acidic conditions.
This study investigates the effect of acidity on the tracking and erosion resistance of silicone rubber composites and associated degradation mechanisms as foundation for the development of reliable material composition for harsh acidic environments. The influence of inorganic fillers in modifying the silicone rubber material design to resist the acidity effect and tracking and erosion is presented as the foundational step towards development of suitable silicone rubber composites for acidic environments. To this end, the composites are pre-stressed with acidity following the ISO-1817 standard for evaluating the effects of liquid immersion on rubber materials and subsequently tested in the standard inclined plane tracking and erosion test (IPT) in accordance with the IEC-60587, followed by the physiochemical and thermal material characterization.