Interface Resistivity - A New Method for Selection and Evaluation of FRP Rod - Housing Interface Performance

摘要

Interface between silicone rubber (SIR) housing and fibre reinforced plastics (FRP) rod is a macroscopic and internal interface in composite insulators. Generally speaking, interface always become the weak point of the whole composite structure, such as weak adhesion, moisture intrusion, impurities, etc. Interface resistivity is proposed as a sensitive parameter to evaluate the electrical property of the interface between FRP rod and SIR housing in this paper. A new-designed electrode system, which is called four-electrode system, is designed and realized to measure the interface resistivity. The high voltage electrode and measurement electrode are embedded between the SIR layer and FRP substrate. Interface resistivity reduced 2 - 4 orders of magnitude after deionized water permeation, and the types and concentrations of solutions influenced the measurement results of the interface resistivity. Among them, the permeation of high concentration nitric acid caused the hydrolysis of saline coupling agent which was used as adhesive agent at the interface, and the decline of interface resistivity of 6 - 8 orders of magnitude was not reversible after dried at room temperature. Furthermore, some influencing factors on the measurement of interface resistivity was studied. Thickness of silicone rubber had most influences on the change of interface resistivity, gap width between measurement and high voltage electrodes less influences while the thickness of embedded electrodes within the range of 20 - 100 nm almost no influences. Interface resistivity method is a very good method to study interface performance, and to select interface coupling agent and insulator production process.