Research On The Non-linear Conductivity Characteristics Of Nano-Sic/Silicone Rubber Composites

Silicon carbide (SiC) is an inorganic material which has non-linearconductivity characteristics. When mixed nano-size SiC into silicone rubber(SIR), the composites can achieve non-linear conductivity characteristics also. Inthis paper, the non-linear conductivity properties of5wt%,15wt%,30wt%,45wt%nano-SiC/SIR composites are investigated. The relationship betweenconductivity and temperature of30wt%,45wt%nano-SiC/SIR composites arealso researched. The relationship between conductivity and electric fieldstrength is obtained. Dielectric spectroscopy properties of different loading nano-SiC/SIR composites are measured by broadband dielectric spectroscopy. Theresults show that the conductivity of the nano-silicone rubber compositesincrease with SiC content increasing. With the increase of nano-SiC content, theelectric field strength at the turn point value decreases. It indicates that theconduction behavior of nano-SiC/SIR composites had changed. Dielectricspectroscopy experiments showed that the permittivity of SiC/SIR compositesincreases with SiC content increasing at room temperature. When the frequencybelow1Hz, the dielectric loss of nano-composites increase with the content ofsilicon carbide decreasing, when the frequency is more than1kHz, the dielectricloss of nano-composite increases with SiC content increasing. In order to knowthe effect of non-linear SiC/SIR composites on homogenizing electric fielddistribution, the electric field distribution of cables termination and compositeinsulators are simulated by finite element method. The results show that theSiC/SIR composites can homogenize the electric field distribution of cabletermination and composite insulators effectively. With the increase of non-linearconductivity level, the maximum electric field value of electric stress of cable termination decrease. When using45wt%nano-SiC/SIR composites, themaximum electric field value of high voltage terminal and ground terminaldecrease extremely. Moreover, through the breakdown test, we know that thecontent of the nano-SiC reach a certain level, the breakdown strength of SIRdecrease.