In this paper, the effect of Al2O3 on physical and electrical properties of ZnO varistors was investigated. After adding different amounts of Al2O3 to ZnO varistors, green and fired density and 3-point bending strength were measured. Also, microstructural analysis was evaluated by SEM. Finally, the optimum values for nonlinear coefficient (α) and breakdown voltage were obtained as 50 and 638 v/cm respectively.
Keywords: varistor, aluminum oxide, physical properties, electrical properties, nonlinear coefficient, breakdown voltage.