Electrical Tracking, Erosion and Fire Retardancy Performance of Silicone Rubber Insulation Containing Aluminum Trihydrate, Graphene and Glass Fiber Additives

Silicone rubber composite is a priority electrical insulating material used in high-voltage outdoor insulation applications. Low electrical tracking/erosion and poor flame resistance performance of silicone rubber once ignited, substantially reduce its working life. This paper attempts to investigate tracking/erosion performance of room temperature vulcanized (RTV) silicone rubber along with flame retardant parameters using aluminum trihydrate (ATH), graphene nanosheets (GN) and milled glass fiber (GF) additives. The inclined plane test (IPT) was performed in line with criteria defined in IEC 60587 using step-up tracking voltage method while flame retardancy is evaluated according to ASTM E 1354.0 using a cone calorimeter. Results suggest 30% of ATH assists in improving physical tracking/erosion resistance of pristine silicone elastomer rubber by impeding development of leakage current and a great reduction in maximum average temperatures on the surface of RTV2. Further improvement in performance of RTV2 is achieved through introduction of 1% of GN and 5% of GF as seen in RTV4. Moreover, 30% of ATH reduces heat release rate and smoke production rate, and this trend is improved with the introduction of GN/GF. RTV4 has pop up as the most promising silicone rubber composite with excellent electrical tracking, erosion, and flame resistance performance relative to its counterparts in this study.