How nonlinear V-I characteristics of single ZnO microvaristor influences the performance of its silicone rubber composite

Microvaristor ceramics blended with insulation polymers can function as nonlinear dielectrics, which possess self-adaptive electrical parameters varying with the applied field. Broadening the switching (electric) field of the nonlinear dielectrics for their applications in various apparatus and voltage class is an important issue. This paper prepared ZnO microvaristor ceramics with different grain size through controlling the sintering temperature, as well as the microvaristor ceramic/polymer composites (MCPC) with different filler concentration, filler diameter, and filler grain size. The nonlinear V-I characteristics of both the single ZnO microvaristor filler and the MCPC were measured. The switching field of the MCPC is found to be adjusted in a wider range by controlling the filler grain size. The relationship between the nonlinear conducting behavior of single filler and the composite are analyzed. Suggestions were proposed for the preparation of ZnO microvaristor fillers to meet specific field grading requirement for MCPCs.