涂覆硅脂对电缆附件绝缘溶胀机理及影响因素

The interface between two insulations in cable accessory is always in a complex environment including electricity and heat. Besides the attachment and design of accessory, the silicone grease coated on interface also plays an important role in keeping the reliability of the interface. So far there has little research about the swelling effects of silicone grease on silicone rubber and its influencing factors. In this paper, based on the silicone grease used for cable accessories, the influences of the heat aging, the corona discharge aging, and the aging of the gas(ozone) produced by corona discharge on swelling of silicone grease on the surface of silicone rubber and the performance of swelled silicone rubber were studied. The results showed that the three types of aging differently damaged the surface microscopic morphology of silicone grease and silicone rubber. The silicone grease of samples after corona aging turned dried and cracked, and a number of dendritic cracks appeared on the surface of the silicone rubber. The results from the measurements of the interfacial breakdown voltage between silicone rubber and cross-linked polyethylene (SR/XLPE), the mechanical performance, and infrared spectroscopy of swelled silicone rubber after different aging show that corona aging will obviously reduce the interfacial insulation strength and mechanical properties of silicone rubber. Additionally, it is found that heat aging, gas aging and corona aging all accelerate the swelling process of silicone grease into rubber, and the promoting effect will reduce sequentially. Thermal aging increases the diffusion rate of silicone grease in silicone rubber by increasing the relative motion between silicone grease and silicone rubber molecules. Gas aging and corona aging will destroy the cross-linked structure of silicone rubber by strong oxidants such as ozone and high energy charged particles to promote the swelling of silicone grease.