Impacts of large temperature difference on the sealing performance of fluorosilicone rubber

Abstract

As one of the promising alternative sealing materials for oil-impregnated capacitors, fluorosilicone rubber (FVMQ) is particularly used in extreme temperature conditions. This study investigates the effects of large-temperaturedifference cycling on the sealing performance of FVMQ, with specimens impregnated in benzyltoluene and subjected to cyclic temperatures from -50 ℃ to 105 ℃. Mechanical properties and microstructure were characterized at aging intervals of 0, 30, 60, and 120 days. After 120 days, the mass and volume increased by 2.21% and 3.31% respectively, while the hardness decreased from 73.8 HA to 70.5 HA. Microstructural deterioration with surface roughening and cracking was observed in immersed specimens. Notably, the compression deformation of impregnated specimens (8.90%) was lower than that of non-impregnated ones (11.38%). This study provides experimental data for capacitor sealing design optimization and compatible material selection.