Enhanced thermal aging resistance of binary mixed natural ester insulating oil by APTES surface-modified SiC nanoparticles

Abstract

Natural ester is expected to become a new type of insulating medium, but its properties still need to be improved. Nanoparticles are currently regarded as highly promising additives in insulating materials. This paper aims to investigate the thermal aging characteristics of nano-modified natural ester insulating oil. Specifically, APTES surface-modified nano-SiC was added to the mixed natural ester, followed by an accelerated thermal aging experiment at 130 °C for 68 days. The experimental results suggested that the nano APTES-SiC reduces the generation rate of water and acids in the insulation system. After thermal aging, the breakdown voltage of the modified insulating oil decreased by 14.39 %–67.2 kV, compared to a 16.4 % decline in the unmodified oil, which exhibited higher dielectric loss and acid value. Additionally, the molecular simulation results indicated that the nano APTES-SiC enhances the interaction and hydrogen bonding network of polar molecules with insulating oil. At 343K, the interaction energy increased by 12.35 % and the number of hydrogen bonds increased by 31.18 %, reducing its possibility of hydrolysis with cellulose. In summary, through experimental and simulation results, it was found that nanoparticles significantly improve the thermal stability of the oil paper system, providing greater application prospects for nano modified insulating oil.