Comparison of Properties of High-Temperature Vulcanized Silicone Rubber between Natural and Artificial Chalking

Chalking is one of the most important indicators for assessing the aging degree of high-temperature vulcanized silicone rubber (HTV-SR) for composite insulators. Existing artificial chalking methods are able to effectively simulate the chalking phenomenon, but the equivalence between artificial and natural chalking still remains unclear. In this paper, both naturally and artificially chalking samples are obtained. Then the surface morphology and chemical properties of chalked samples are methodically characterized. Finally, artificial and natural chalking degrees are quantitatively compared and analyzed by linear fitting. Experimental results show that the artificially chalking process has a great influence on the filler precipitation but little change to absorption peaks of chemical bonds. Besides, the content of highly oxygenated Si atoms is increased obviously. It turns out that the degree of artificial chalking in this paper is approximated to the degree of mildly natural chalking (aging for 11 years on the grid). This work presents a detailed comparison of properties of naturally chalking (especially with different aging years) and artificially chalking HTV-SR samples.