Room temperature vulcanized silicone rubber（RTV） coatings are widely used in porcelain and glass insulators due to their good hydrophobicity and anti-pollution flashover performance. With the increase of insulator operating time

the electrical performance of RTV coatings will be decreased by aging phenomena such as pulverization

shedding

and hydrophobicity losing. In current study

the aging mechanism of RTV coatings has not been clearly researched. Therefore

we investigated the influence of coating thickness on its aging characteristics under AC corona. The macrostructure

microstructure

hydrophobicity and chemical composition of the coatings with different thickness were analyzed from the following aspects

such as

appearance examination

hydrophobicity test

Fourier transform infrared spectroscopy（FTIR）

scanning electron microscopy（SEM）

and X-ray photoelectron spectroscopy（XPS） tests. The results show that

after corona aging

a black material precipitates on the coating surface and shows obvious partition structure. At the same time

holes

cracks

particles and other aging characteristics of coatings with different thickness can be observed. The hydrophobicity and migration properties of coatings with 0.6～0.8 mm thickness are much better than those with 0.3～0.5 mm thickness. FTIR and XPS results show that the silicon oxide layer thickness and the broken chain layer thickness will decrease with the increase of coating thickness. The high oxidation state of silicon content of 0.6 mm coating is obviously higher than that of 0.3 mm coating. The influence of corona aging on the physical and chemical properties of the coating decreases with the increase of coating thickness.