Synthesis of h-BN/Nanosilica Hybrid Reinforced Room Temperature Vulcanizing Silicone Rubber (RTV SiR) Nanocomposites for High Voltage (HV) Insulators

High voltage (HV) insulators play a crucial role in power transmission, microelectronic components, transformer systems, and other energy applications. However, they often face challenges related to the surface accumulation of moisture and solid contaminants, which can lead to thermal runaways and flashovers. Such problems ultimately reduce the insulator’s durability and overall efficiency. To address these concerns and minimize maintenance costs, polymeric composite-based coatings have become a popular solution.

This study focuses on the fabrication of room temperature vulcanizing silicone rubber (RTV SiR) based nanocomposites as external coatings for HV insulators. The primary objective is to enhance the thermomechanical and degradation-resistant properties of RTV SiR using hexagonal boron nitride (h-BN) and nanosilica reinforced hybrid filler. Using perflouro-octyl-triethoxysilane (FTS) functionalized h-BN (h-BNNS), improved filler dispersion is achieved within the SiR matrix, which offers increased mechanical strength and hydrophobicity. Different loadings of h-BNNS, h-BNNS/SiO₂, and SiO­₂ are prepared using a facile synthesis method and dispersed homogeneously into the RTV SiR matrix. The resulting nanocomposite is spray-coated onto ceramic tiles to evaluate the impact of filler type and loading amount on thermomechanical stability, surface wettability, and resistance to surface tracking.

Through characterization, h-BNNS/SiO₂ reinforced RTV SiR nanocomposites exhibited a manifold increase in electrical breakdown strength in the Inclined Plane Test (IPT) in comparison to pristine RTV SiR, while also showing uniform filler dispersion using Scanning Electron Microscopy (SEM). It also outperformed pristine RTV SiR in Thermogravimetric Analysis (TGA), Water Contact Angle (WCA), and Dynamic Mechanical Analysis (DMA), indicating the nanocomposite’s superior thermal stability, dielectric properties, interfacial interactions, and minimal agglomeration, rendering it ideal for energy applications in harsh environments.