Adjusting nonlinear characteristics of ZnO-silicone rubber composites by controlling filler's shape and size

Nonlinear composites consisting of insulation matrix and functional fillers are potential materials for field grading and stress control due to their field-dependent electrical parameters. One main task for the application of nonlinear composites is to tailor their nonlinear property to meet the specific field grading requirement. In particular, switching field is the most important parameter as it determines the critical electrical field under which the composite begins to exhibit nonlinear property. In order to investigate how to control the switching field of the composite through the size and shape of the fillers, the paper has prepared ZnO microvaristor /silicone rubber composites with spherical and irregular-shaped fillers in different diameter ranges and then measured the nonlinear V-I characteristics of the prepared composites. The influence of the filler shape and size to the switching field of the composites is concluded and the result can be well understood through the theory of conducting composites and simulation for the conducting behavior of the nonlinear composites.