Aging Characteristics of Ceramifiable Silicone Rubber Nanocomposites Exposed to Electrolytic Solution

The capability to transform into a flame-retardant ceramic body when encountering high temperatures makes low melting glass (LMG) powder an effective additive for room temperature vulcanized (RTV) silicone rubber composites, which are used as coating materials for outdoor high-voltage insulators operating in harsh environments. In this context, the present study examines the impact of nano LMG powder (LMGP) on the aging characteristics of 5 wt% boron nitride (BN)-doped silicone rubber nanocomposites exposed to a strong electrolytic aqueous ammonium chloride (NH4Cl) solution. LMG nanofiller was added in varying weight percentages of 3 and 7 wt%. Except for the 7 wt% LMG-doped composite, a distinct dip in weight gain, indicating higher degradation and detachment of filler particles, was noted in all the composites during diffusion test. Aging-induced deterioration of surface morphology is well evident in 3-D microscopy, contact angle, and Fourier transform infrared (FTIR) spectroscopic test results, which clearly demonstrate increased surface roughness and scissioning of side chains (Si-CH<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{{3}}\text {)}$ </tex-math></inline-formula> and backbone chains (Si-O–Si) in silicone rubber matrix of all the composites postaging. Furthermore, antipollution performance and thermal properties of all the test specimens were evaluated through inclined plane tracking and erosion test, thermogravimetric analysis (TGA), and IR thermography. The test results demonstrated that LMG-doped composites showed better tracking and erosion resistance, higher thermal stability, and lower surface temperature distribution during inclined plane tracking (IPT) compared to the only BN specimen before and after aging. The experimental results revealed that the 7 wt% LMG composite exhibited better resistance to degradation caused by the NH4Cl solution.