直流电压下Al2O3/硅橡胶复合材料的表面电荷消散机制研究OA

The phenomenon of surface flashover induced by the accumulation of surface charge has emerged as a significant impediment to the secure and stable operation of electrical grids.Methods for regulating the surface charge characteristics of insulating materials predominantly encompass three approaches:optimizing the geometry of insulating materials,surface treatment,and nanomodification.In a comprehensive assessment of cost-effectiveness,reliability,and stability,nanomodification stands out as a favorable choice due to its cost-efficiency,operational flexibility,and ease of implementation.Accordingly,this paper introduces varying concentrations of nano-and micro-scale Al2O3 into pure silicone rubber through nanomodification techniques to enhance the dissipation rate of surface charge in silicone rubber. Firstly,a surface potential measurement system and a surface flashover measurement system were set up.Subsequently,the surface charge dissipation characteristics of silicon rubber composites with varying concentrations of nano-and micro-scale Al2O3 were studied.The positive DC surface flashover voltage was measured with uncharged and charged silicon rubber composites.The surface flashover voltage of silicon rubber composites during the natural dissipation process was recorded.The results of surface conductivity,volume conductivity,trap density,and scanning electron microscopy(SEM)were analyzed. All of nano-and micro-scale Al2O3/silicone rubber composites,ranked in descending order,exhibit the average surface charge density as follows:PS＞MS-10＞MS-20＞MS-30＞NS-10＞NS-20＞NS-30.At 65 min,the average surface charge density of the pure silicone rubber sample decreased by 56.81%.The average surface charge density of nano-and micro-scale Al2O3/silicone rubber composites decreased within 63.55%～68.56%and 68.75%～70.06%,respectively.Combined with the results of conductivity and the density of deep and shallow traps,the incorporation of both nano-and micro-scale Al2O3 particles introduces shallow traps within the silicone rubber.The aggregation of nano-scale Al2O3 is primarily accountable for this phenomenon,and the larger size of micro-scale Al2O3 particles weakens the interface interaction with silicone rubber,potentially introducing impurities and voids.These shallow traps result in an augmentation of both volume and surface conductivity,consequently facilitating the dissipation of surface charge. The following conclusions can be drawn.(1)The surface potential of all Al2O3/silicone rubber composites exhibits a bell-shaped distribution pattern,with surface charge primarily dissipating through pathways within the silicone rubber.(2)While the introduction of Al2O3 leads to a reduction in the surface flashover voltage,the Al2O3/silicone rubber composites exhibit a faster recovery rate of surface flashover voltage during the surface charge dissipation.(3)After a dissipation time of 60 minutes,the surface flashover voltage of pure silicon rubber,nano-scale Al2O3/silicon rubber composite,and micro-scale Al2O3/silicon rubber composites can be restored to 86.53%,96.01%,and 94.18%,respectively.(4)If only improving silicone rubber's surface charge dissipation rate,a 30%nano-scale Al2O3/silicone rubber composite is recommended.If considering both the dissipation rate of silicone rubber surface charge and the surface flashover voltage simultaneously,a 10%micro-scale Al2O3/silicone rubber composite is recommended.