Modélisation et elaboration des varistances à coefficient de température positif

Abstract

Several research studies are conducted for the development of varistors , especially based zinc oxide varistors into account their advantages. This is a component having a variable electrical resistance depending on the voltage applied to its terminals. The content of this thesis therefore aims to develop models zinc oxide based varistors. Our study addresses two main parts: The first part concerns the achievement of varistors based on zinc oxide doped barium titanium oxide without other additives. They were developed through solids and conventional sintering. The second part was devoted to the preparation of ZnO-based varistors nano- powder doped (98 mol% ZnO , 0.5 mol% Bi2O3, 0.5 mol% Sb2O3, 0.5 mol% Co2O3, 0.5 mol% MnO2 ) by liquid method through two sintering techniques , conventional sintering and microwave sintering. The two used techniques have been compared for determining the advantages of each one. Keywords: Varistors, nonlinearity coefficient, Microstructure, electrical properties, conventional sintering, microwave sintering.